Which of the following is a true statement regarding DX systems?

In DX (Direct Expansion) systems, the operational process involves refrigerant directly evaporating in the evaporator coil, which is a crucial aspect of how these systems provide cooling. The evaporator is where the refrigerant absorbs heat from the indoor air, leading to a reduction in air temperature as it changes from a liquid to a gas. This absorption of heat is what makes DX systems effective for cooling applications. The statement about flash gas highlights a fundamental operation within these systems, where the refrigerant undergoes a phase change, essential for the overall cooling process.

The other options present statements that don't accurately reflect the characteristics and functionalities of DX systems. Thus, focusing on the operation and design principles of DX systems clarifies why the given option regarding flash gas accurately represents the true nature of such systems.